(1) Field of the Invention
The present invention relates to a method of forming crimps in high tensile modulus filaments. More particularly, the present invention relates to a method of forming crimp in artificial filaments having a high tensile modulus of elasticity of 5,000 kg/mm.sup.2 or more, by a compression crimping procedure, to provide crimped high tensile modulus filaments which can be connected to staple fibers having an enhanced spinning property.
(2) Description of the Related Arts
It is known that artificial crimps can be imported to artificial filaments by a compression crimping method or a gear crimping method. It is also known that, from the view point of productivity, the compression crimping method using a stuffing box is best utilized, and accordingly, attempts have been made to crimp artificial high tensile modulus filaments, for example, para-type aramide filaments having a tensile modulus of elasticity of 7100 kg/mm.sup.2, by the compression crimping method using the stuffing box.
Where the compression crimping procedure is applied to a tow of the high tensile modulus filaments in a compression crimping apparatus, it is often found that, a short time after the start of the crimping procedure, the bundling condition of the filament tow supplied to the crimping apparatus is in disorder and at the same time, shaking of the crimping apparatus occurs, and thus the crimping procedure cannot be continued. Also, the resultant crimped filaments have unsatisfactory crimping properties, and thus are not practically usable.
Where the same crimping procedure as mentioned above was applied to other high tensile modulus filaments, for example, steel filaments having a tensile modulus of elasticity of 20,000 kg/mm.sup.2 and glass filaments having a tensile modulus of elasticity of 7,000 kg/mm.sup.2 shaking of the crimping apparatus occurred in the same manner as mentioned above and the resultant crimped filaments exhibited unsatisfactory crimping properties.
When the crimped high tensile modulus filaments were subjected to a spinning procedure in the form of staple fibers, it was found that a lap of the fibers was wound around a carding roll, and thus the spinning procedure could not be continued.
Accordingly, the provision of an effective method of imparting satisfactory crimps to high tensile modulus filaments by using a compression crimping apparatus is strongly desired.